Interplay between charge-lattice interaction and strong electron correlations in cuprates: phonon anomaly and spectral kinks

TL;DR

This study explores how strong electron correlations and charge-lattice interactions in cuprates cause phonon anomalies and spectral kinks, aligning theoretical predictions with experimental observations.

Contribution

It demonstrates the impact of nonadiabatic electron-phonon interactions on phonon spectral functions and electron dispersion in cuprates using a t-t'-J model with exact diagonalization.

Findings

Splitting of phonon spectral function at specific wave vectors.

Low energy kink in electron dispersion due to nonadiabatic coupling.

Higher energy kink influenced by electron correlation strength.

Abstract

We investigate the interplay between strong electron correlations and charge-lattice interaction in cuprates. The coupling between half breathing bond stretching phonons and doped holes in the t-t'-J model is studied by limited phonon basis exact diagonalization method. Nonadiabatic electron-phonon interaction leads to the splitting of the phonon spectral function at half-way to the zone boundary at $\vec{q}_s=\{(\pm \pi / 2, 0), (0, \pm \pi / 2) \}$ and to low energy kink feature in the electron dispersion, in agreement with experimental observations. Another kink due to strong electron correlation effects is observed at higher energy, depending on the strength of the charge-lattice coupling.